Generelle Morphologie der Organismen

Ernst Haeckel's Generelle Morphologie der Organismen (1866) presented his evolutionary ideas, though it received little attention from the scientific community at the time. Haeckel, a proponent of Darwinism, proposed that individual development (ontogeny) briefly recapitulates the evolutionary history of a species (phylogeny), a concept known as the biogenetic law. He sought to explain both inorganic and organic nature under unified physical laws, speculating on the spontaneous origin of life from inorganic matter and tracing evolutionary lines from simple organisms to complex ones. While his concepts of recapitulation were later found to be inaccurate, Haeckel's work stimulated discussion on important biological questions and contributed to the understanding of invertebrates. Morphology itself is the study of the size, shape, and structure of organisms and their parts.123